As the smallest structural components of graphene nanoribbons, polyperinaphthalenes, commonly known as rylenes (see FIG. 1) and their derivatives are of intense current interest. Long-chain rylenes absorb a broad spectrum of light and may display electrical conductivity. If rylenes are to find application as electronic or photovoltaic components, their economical and large-scale synthesis is essential.
It is surprising that efficient and scalable synthetic routes to the parent structures terrylene (3) and quaterrylene (4) have not been described. See again, FIG. 1. These important hydrocarbons were first reported many years ago but the best current methods still follow classic Scholl conditions, which are suitable only for small scale reactions.
Reference to the Scholl reaction above is more specifically a reference to the heating naphthalene with solid AlCl3 resulted in a relatively low yield of perylene (milligram quantities). This is a two-step process, with initial formation of 1,1-binaphthyl, followed by intramolecular cyclization. Similar dimerization of perylene to quaterrylene was reported. See, e.g., Aromatic Hydrocarbons. XLVII. Synthesis of Benzologs of Perylene and Bisanthene, Chem. Ber. 1949, 82 46-60; Catldo et al, On The Way to Graphene: The Bottom-Up Approach to Very Large PAHs Using the Scholl Reaction, Fullerenes, Nanotubes, Carbon Nanostruct. 2011, 19 (8), 713-725.